1. Field of the Invention
The present invention relates to a display device using light emitting elements and a manufacturing method thereof. More particularly, the invention relates to a multicolor display device and a manufacturing method thereof.
2. Description of the Related Art
In recent years, the development of a display device using light emitting elements has been advanced. A display device that is currently under development is the one in which one pixel is divided into three sub-pixels each corresponding to one of R (Red), G (Green) and B (Blue) that are the three primary colors of light, and a gray scale display is performed in each of the sub-pixels for RGB, and thereby performing a multicolor display. When performing the multicolor display, typically, light emitting elements are formed by using light emitting materials corresponding to RGB, or a light emitting element that emits white light is used in combination with RGB color filters. Alternatively, a light emitting element that emits any color light is used in combination with a color conversion material typified by a fluorescent material.
In LSI technologies, well known is a variable channel-size MOSFET including a main gate as well as a control gate that is provided between the main gate and a source region and between the main gate and a drain region (see Non Patent Document 1, for instance).
[Nonpatent Document 1] Naoki Nakanose and five others, SSDM2003, pp. 424-425
In the case of a multicolor display being performed by using sub-pixels, even when a current with the same current density or the same amount of current is supplied to a light emitting element in each sub-pixel, luminance varies for each light emitting element of RGB. Further, in the case of a light emitting element that emits white light being used in combination with color filters, or a light emitting element that emits any color light being used in combination with a color conversion material typified by a fluorescent material, the light transmittance of each color filter varies as well as the conversion efficiency of the color conversion material, and thus the obtained luminance has variations.
In the case of displaying white color in this state, luminance varies for each sub-pixel corresponding to each color, therefore, white may be tinged with red, blue or green, and white color cannot be displayed accurately.
Therefore, in order to achieve the uniformity in luminance of each sub-pixel, the amount of current or the current density flowing in a light emitting element is required to vary for each color.